An underwater lighting device known in the state of the art, particularly from document EP 2 594 245, comprises:
an electronic board comprising a surface, called front surface,
light-emitting means assembled on the front surface of the electronic board,
a protective cover arranged to protect the electronic board and the light-emitting means,
heat transfer means arranged to transfer the heat generated by the light-emitting means to the aquatic environment.
The heat transfer means comprise a metal plate assembled on the surface, called rear surface, opposite to the front surface of the electronic board. The metal plate is intended to be submerged in the aquatic environment to benefit from a heat exchange with the aquatic environment in order to be cooled. The metal plate thus enables to dissipate the heat essentially generated by the light-emitting means, such as light-emitting diodes, particularly power diodes. Indeed, in the absence of heat transfer means, it can be observed that the temperature of the electronic board strongly increases, which may deteriorate the electronic board and the light-emitting means in case of an extended operation of the device.
However, such a device of the state of the art is not fully satisfactory since it requires a conical seal, typically made of rubber, arranged between the metal plate and the protective cover, to prevent the coming into contact of the electronic board and of the light-emitting means with the aquatic environment.
Now, such a conical seal requires the forming of shoulders in the protective cover to create support surfaces for the seal. The forming of shoulders in the protective cover also results in the forming of shoulders in the metal plate. Indeed, the metal plate partly rests on the rear surface of the electronic board, and partly on the shoulders of the protective cover. Accordingly, such a device of the state of the art introduces a complexity in the manufacturing thereof by specific machinings of the protective cover and of the metal plate.
Further, the metal plate is submitted to the external pressure of the aquatic environment. Now, the metal plate, which is rigid, transmits high stress to the seal. The seal undergoes compressive losses due to differential expansions with respect to the metal plate, which adversely affects the lifetime of the seal, and thereby of the device.